Reference hearing threshold levels for chirp signals delivered by an ER-3A insert earphone
* Department of Electrical Engineering, Hearing Systems, Technical University of Denmark , Lyngby , Denmark.International journal of audiology (Impact Factor: 1.84). 08/2012; 51(11):794-9. DOI: 10.3109/14992027.2012.705901
Abstract Objective: To establish reference hearing threshold levels for chirps and frequency-specific chirps. Design: Hearing thresholds were determined monaurally for broad-band chirps and octave-band chirps using the Etymotic Research, ER-3A insert earphone. The chirps were presented using two repetition rates, 20 and 90 stimuli/s, and with alternating polarity in blocks of one second duration. The test procedure and test conditions were in accordance with the recommendations given in ISO 389-9 (2009) . The ascending method ( ISO 8253-1, 2010 ) was applied using a step size of 5 dB. The chirps were played back from a Tucker Davies Technologies System II, and a Matlab program controlled the test setup. The results are specified in dB peak-to-peak equivalent threshold sound pressure levels (dB peETSPL). Study sample: The test group consisted of 25 otologically-normal young adults (age 18-25 years). Results: The results are in good agreement with the results from another investigation of hearing thresholds using the same chirp stimuli, and the values for the octave-band chirps are in line with the standardized reference values for corresponding tone bursts ( ISO 389-6, 2007 ). Conclusions: The results of the present investigation are relevant for the international standard on short duration signals, ISO 389-6 (2007) .
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ABSTRACT: Narrow band CE-chirps® were developed to provide a better synchronization of neural response due to the compensation of the travelling wave delay in the basilar membrane. These stimuli combined with a detection method that includes higher response harmonics on the auditory steady-state response (ASSR) recording was studied in this research. Objective 1- to establish air conduction thresholds for ASSR to narrow band CE-chirp® in normal hearing full-term neonates; 2- describe the test time needed for the above in one ear and 3- to compare the results in infants and normally hearing adults. Method ASSR to air-conducted stimuli were obtained in 30 full-term neonates (14 girls and 16 boys) with an average age of 34.3 hours of life. All neonates were presented presence of transient-evoked otoacoustic emissions (TEOAE) and result “pass” in automatic ABR at 35dBnHL before ASSR test. ASSR thresholds of both ears of 10 normal hearing adults (5 girls and 5 boys) varied in age between 23 and 30 years and with hearing thresholds better than or equal to 15 dB HL at all frequencies between 250 and 8000 Hz were recorded to compare with the neonate data. Results The neonate ASSR thresholds estimated from 50% using cumulative distributions were 24.5, 13.5, 7.5 and 10 dB nHL at 500, 1000, 2000, and 4000 Hz, respectively. For the same frequency order, ASSR thresholds estimated from 90% of the neonates were 34.5, 28, 12.5 e 15 dB nHL. It required 21.2 (+5) minutes on average to obtain threshold in each ear in neonates, with a range of 12 to 29 minutes. When ASSR thresholds recorded in full-term neonates and adults were directly compared, the differences between these groups were not significant for 1000 Hz (p = 0.500), 2000 Hz (p = 0.610) and 4000 Hz (p =0,362). However, at 500 Hz, ASSR thresholds in neonates tend to be greater than in adults (p = 0.001). Conclusion In this study ASSR thresholds estimated from 90% of the neonates were 34.5, 28, 12.5 e 15 dB nHL. It required 21.2 (+5) minutes on average to obtain threshold in each ear and ASSR thresholds to narrow band CE-chirp® in neonates are not significant for adults ASSR thresholds, except at 500 Hz, when the ASSR thresholds in neonates tend to be greater than in adults.
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ABSTRACT: Objective: To evaluate the auditory brainstem response (ABR) amplitudes evoked by tone pip and narrowband chirp (NB CE-Chirp) stimuli when testing post-screening newborns and to determine the difference in estimated hearing level correction values. Design: Tests were performed with tone pips and NB CE-Chirps at 4 kHz or 1 kHz. The response amplitude, response quality (Fmp), and residual noise were compared for both stimuli. Study sample: Thirty babies (42 ears) who passed our ABR discharge criterion at 4 kHz following referral from their newborn hearing screen. Results: Overall, NB CE-Chirp responses were 64% larger than the tone pip responses, closer to those evoked by clicks. Fmp was significantly higher for NB CE-Chirps. Conclusion: It is anticipated that there could be significant reductions in test time for the same signal to noise ratio by using NB CE-Chirps when testing newborns. This effect may vary in practice and is likely to be most beneficial for babies with low amplitude ABR responses. We propose that the ABR nHL threshold to eHL correction for NB CE-Chirps should be approximately 5 dB less than the corrections for tone pips at 4 and 1 kHz.
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ABSTRACT: The aim of this study was to compare the human auditory brain stem response (ABR) elicited by clicks and chirps with overall behavioral hearing thresholds in participants with normal hearing and with sensory hearing loss. The authors hypothesized that ABRs to chirps would be more robust and that thresholds would be more similar to overall behavioral hearing thresholds compared with ABRs to clicks. Twenty-five adults with normal hearing and 25 adults with sensory hearing loss were recruited. Subjects were without middle ear or neurological pathologies at the time of testing. Subjects with sensory hearing loss were separated into mild to moderate hearing loss and mild to severe hearing loss groups. Behavioral hearing thresholds for pure tones were obtained at nine octave and interoctave frequencies ranging from 250 to 8000 Hz; an average of these nine frequencies was calculated for each participant. Evoked potential thresholds were measured by ABRs to click and chirp stimuli. Analyses included wave V absolute latencies and wave V peak-to-peak amplitudes. Thresholds for ABRs to clicks and chirps were compared with each other and with overall behavioral hearing thresholds. ABR thresholds to chirp and click stimuli did not differ significantly for either the normal-hearing or the hearing loss groups. Wave V peak-to-peak amplitude was higher for chirps than clicks, particularly at lower intensities, for all groups. ABR thresholds to chirps were closer to overall behavioral thresholds than clicks in all groups. Moreover, ABR thresholds to chirps did not differ significantly from behavioral thresholds in the two hearing loss groups. ABRs obtained with chirp stimuli provide an efficient method for estimating hearing thresholds in individuals with normal hearing and sensory hearing loss where broadband signals are selected for testing. ABRs to chirps display higher peak-to-peak amplitudes than those obtained with clicks and may provide responses closer to behavioral thresholds. This information could result in improved accuracy in identifying hearing loss and estimating hearing sensitivity for broadband signals in infants, children, and difficult-to-test older populations.
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